5. Fonts and Colors

Understanding fonts and colors can be more complex in
X than on other platforms.

5.1. Fonts Demystified

X knows about various font types, including
bitmaps, Type 1, and as of v4.x, TrueType. The X server can either handle
fonts itself, or sometimes this duty is forked to a font server (of which
there are several). xfs (X Font Server) is the most common
font server in use on Linux.

A font server is not required, as X can handle
most font rendering itself. Font servers are traditionally used for serving
fonts to multiple hosts on a network, but sometimes are also used to provide
enhanced functionality. Additionally, a font server may provide a modest
performance boost by off-loading font rendering to a separate process.

X knows about fonts according to fonts that are in
the "FontPath". This is set initially in
XF86Config. If the X server is handling font duties
itself (i.e. no font server), this will be a list of directories that contain
font files, like:

If a font server is being used, the "FontPath" will point to the
socket where the font server is serving (this is just one possible example):

FontPath "unix/:7101"

In this latter case, the actual font directories that are available will be
configured with the font server (see local documentation), which will use a
similar directory type scheme as shown for XF86Config.

Once suitable fonts have been installed, they must be
"prepared". For most fonts, this means running the
mkfontdir utility (see man page) in the directory where
the fonts are (as root). Type 1 and TrueType require additional steps (see
below). Your vendor has done this for any fonts that were included with your
distribution. So, this will only need to be done for fonts that you add. For
newly added fonts to become visible to X,
you will need to run the appropriate
xset commands to either modify the existing FontPath, or
re-read it (see man page). Or, re-initialize your font server.

The first command may not be necessary on newer distros (since it's done by
the init script in some cases). And the font server configuration would need
to be modified, if this is a new directory. Example: re-initializing with no
font server:

The "xset +fp" would not be necessary if the
directory is already part of the FontPath.

xlsfonts | less can be used to list what fonts are known,
and thus available, to X and its clients. Run
xlsfonts | less, and you also can get an idea of the font
definition as understood by X. Font resources are
specified quite explicitly, and it may seem complex at first. The X
Logical Font Description ("XLFD") is the full
description for any given font. The XLFD looks like:

-adobe-helvetica-medium-r-normal-*-*-120-*-*-p-*-iso10646-1

Where each field, left to right is:

fndry - font foundry, the company or individual
which made the font.

fmly - font family, the popular nickname of the font

wght - font weight (bold, medium, etc.)

slant - font slant (italics, oblique, roman
(normal), etc.)

sWdth - font width (normal, condensed, extended, etc.)

adstyl - additional style (sans serif, serif, etc.)

pxlsz - pixel size, the number of pixels
vertically in a character

ptSz - approximate point size of the text
(similar to pxlsz)

resx - horizontal resolution, in dpi

resy - vertical resolution, in dpi

spc - spacing, only useful, apparently, in the
Schumacher fonts

avgWidth - average character width of the font

rgstry - the recognized registry that lists
the font

encdng - nationality encoding

The "*" acts as a wild-card character. In fact, if not every
field is specified, the X server will take the first match it finds in
the FontPath. This is why it is best to order the FontPath with preferred
fonts coming first since some programs will deliberately specify fonts
"loosely" so that your system has some discretion.

The program xfontsel (X
Font Selector) may be useful. Try launching it now. You will see
nothing helpful in the main window at first, but try holding the left button
down on the fndry button. If all your fonts are
in order, you will see a menu of selections such as adobe and b&h and
bitstream and so forth. Select one such as
b&h and you will notice that the font in
the lower window changes to something intelligible. This is the way
fonts are selected with this program; starting from the left, which is the
most general selection, and moving toward the right, to the more specific
options. Selecting an option toward the rightmost end will not make much
sense before the foundry, for instance, is selected, because the options are
generally ordered by their dependence on each other.

When you select from the fmly selection,
you will see most of the options grayed out, and only three remaining. That
means that these three are the only families of font made by this foundry.
Some families appear under more than one foundry, for instance, both
Adobe and Bitstream make a
variation of the Courier font. Now you can select the wght, and so forth. After you get far enough you will
have narrowed it down to the font that you want. You don't necessarily have
to fill in all the options to choose a single font, there's not
that many fonts on your system! The options that you do
not select will be represented by a *
indicating that any option will do in that spot, and gives X some leeway.

When you are satisfied with your font selection, hit the select button,
and your selection will be placed in the X
clipboard, ready to be pasted into your document or whatever you are working
on. For example, open an xterm window and
type in something like xterm -font followed by
an opening quotation mark. Then point to that spot on your screen, and click
your middle mouse button (or click both the left and right, if you are
middle-button impaired). This will paste the selection from the clipboard,
which should be the font you just selected. Then enter the closing quote, and
hit Enter. For instance, a nice big xterm with a Courier font specified would look like
this: xterm -font
"-adobe-courier-medium-r-*-*-14-*-*-*-*-*-*-*".

If you've found a font you prefer, this can permanently be used by placing the
font definition in the appropriate configuration file (see above).

Note that you can also limit the number of fonts that you want
xfontsel to display with the command line option
-pattern, followed by a quoted font specification, as
discussed above.

The xfd utility is also helpful for examining
individual fonts. If launched with a command line such as xfd
-fn fixed, it will show you the complete character set for that font.

KDE and GNOME have
their own utilities that are not quite as obtuse ;-)

5.1.1. Type 1 and TrueType Fonts

The fonts provided with XFree86 are of limited use for many of us,
considering that about the only place you'll find fonts of that kind, are
used in the X Window System itself for the most part. Unfortunately many
media junkies, web designers and fontaholics work in operating systems that
rely on other formats. And then, there often does not seem to be much
emphasis by some distributions on making the best of the default fonts
either.

Type 1 fonts, most commonly used in conjunction with PostScript document
formats, are the traditional standard in Unix and Linux environments. You
should have a reasonably good starter selection installed already. Or, more
can be found for free on the Internet with considerable ease, and Try ftp://ftp.cdrom.com/pub/os2/fonts/
for starters. Type 1 are scalable fonts, and have many of the same benefits
of the better known TrueType fonts. If you don't have a good selection of
TrueType fonts installed, then Type 1 is what you want for most GUI
applications. But again, this is not standard on other platforms, and can
present problems when viewing documents (e.g. web pages) that are designed
with "other platforms" in mind.

TrueType fonts started with Apple, and later were licensed by Microsoft. So
people migrating from non-Unix platforms are already familiar with these high
quality fonts. Unfortunately, there are not many quality TrueType fonts under
a suitable license, and thus there are not many included with Linux
distributions. And the ones that are, often are not as high quality. Also
unfortunately, TrueType has become somewhat of a standard on the Web and in
other venues, and not having good TrueType fonts can be a detriment.
XFree86 also seems to render TrueType a little better than Type1.

That is the bad news. The good news is that any TrueType font included with
any version of Windows, or any Windows applications, should work on Linux.
Though you will have to take some additional steps to integrate them. This
particularly helps web browsing where X's
bitmapped fonts just don't scale well.

We shall not go into detail on installing and configuring these fonts here,
as it is addressed in depth in other documents. See
The Font HOWTO
for general font information, and Type 1 tips.
See The Font De-Uglification
Mini HOWTO,
The Font De-Uglification
Mini HOWTO,
for various X related font tips, especially TrueType.

5.2. Colors

Let's go back to our terminal window and try something. Open an
xterm with a command line like the following:

xterm -fg DarkSteelBlue1 -bg red3 &

Ouch! While that may not be pretty, and you may not do much of your best work
in it, it demonstrates one interesting aspect of X
configuration -- color names. While not particularly precise, this is a nice
way to remember a variety of colors. Note that color names are never
case-sensitive.

The X server will actually deal with color values as a hexadecimal
Red-Green-Blue (RGB) color notation. This would look something like
"#0aff0a" in hex. Not so easy to remember. But
X gives a more mnemonic way of remembering valid
color definitions. These are stored in a text table, typically as
/usr/X11R6/lib/X11/rgb.txt, and is defined in
XF86Config in the "Files" section.

If you are interested, have a look with a text editor. There are many, many
shades defined. I count eighty-three shades of blue in mine, for instance. Brief
snip: